By the end of World War II, with an American infantry platoon carrying as many as four different weapons -- and four types of ammo -- the U.S. Army decided to develop a single weapon that could fulfill multiple roles. The result was the M14. First fielded in 1957, the rugged, accurate new rifle had plenty of stopping power with the standard NATO 7.62 mm round. It first saw major action in Vietnam, where soldiers liked its performance but struggled with the weight of both gun and ammunition. Before long it was phased out in favor of the lighter M16, but a few frontline units still use the classic weapon, primarily as a sniper rifle.

The Wehrmacht hadn't been at war with the Soviet Union for long when it became clear that German infantry with their bolt-action Mausers were often at a disadvantage in firefights with Russian automatic weapons. In response, German armament developers came up with a revolutionary new weapon: the first "assault rifle" (the literal translation of the German Sturmgewehr). The key to its success was a shorter 7.92 mm round that allowed for effective automatic fire and permitted soldiers to carry sufficient ammunition. The Sturmgewehr came too late to play a significant role in World War II, but it wins high marks for innovation.

The relatively poor performance of the Norwegian Krag-Jorgensen rifle used by U.S. troops in the Spanish-American War led American planners to look elsewhere for a standard infantry weapon. They "borrowed" the more effective action found on the German 7mm Mauser, added a few modifications, and produced a magazine-fed rifle that boasted phenomenal accuracy. The 1903 quickly gained a reputation as an outstandingly accurate and powerful firearm -- at the Battle of Belleau Wood in 1918, U.S. Marines armed with Springfields cut down enemy counterattacks from 700 to 800 yards away. The rifle continued in service through World War II and Korea and even saw combat as a sniper rifle in Vietnam.

Looking more like a weapon from a science-fiction movie, the Steyr's only serious "flaw" is the advanced design that seemed to scare away potential customers after its introduction in 1977. In this radically new "bull-pup" configuration most of the barrel, receiver and action, instead of being in front of the operator's firing hand, is all moved back in the stock, resulting in a remarkably compact weapon that is light and easy to handle. The Steyr also features an interchangeable barrel system, a transparent magazine, and optional left or right shell ejection capability.

First produced at the end of the 19th century, the Mauser 98 was the perfect synthesis of the many innovations that rifles had undergone during the late 19th century: smokeless powder, clips that could be fed into magazines and, most of all, its superb bolt action that is still the basis for most modern hunting rifles. The original model 98 was used during World War I to great effect, but when Germany started rearming in the 1930s the rifle received upgrades that made it lighter and easier to sight and shoot. Inevitably outgunned by automatic weapons, the Mauser nevertheless stands as one of the legendary rifles of the modern age.

Inspired by the Sturmgewehr 44, the Belgian manufacturer Fabrique Nationale (FN) originally developed the FAL around the same intermediate round used by the German gun, but when NATO issued the requirement for the longer 7.62 mm, FN altered the design and created a heavy hitter that packs a punch -- and a potent kick. The FAL soon became one of the classic weapons of the Cold War, used by over 50 countries, even if it proved tough to handle in full auto mode. The rifle gave good service to the Australian army in the jungles of Vietnam, to Israeli troops during the Six-Day War and was used by both sides in the fight for the Falkland Islands.

Adopted by the U.S. Army in 1936, the M1 Garand proved to be a tough, heavy battle rifle when it entered combat five years later. General Patton remarked at the end of World War II that the M1 may have been the greatest battle implement ever devised. A bit of a stretch perhaps, but there's no doubt that the M1 was the first successful semiautomatic rifle issued in any quantity that had the ruggedness and accuracy to dominate the battlefield. Over 6.25 million Garands had been manufactured by the time it was taken out of service in the early 1960s.

The standard infantry weapon of British troops from World War I to the 1956 Suez crisis, the Lee-Enfield SMLE (pronounced "smelly") built its reputation on reliability, accuracy and a phenomenal rate of fire. Its magazine carried 10 bullets, the largest capacity of any rifle on the battlefield during the first half of the 20th century. Its short bolt action cocked on closing, and its muzzle cap prevented dirt from clogging the weapon. In the hands of a well-trained infantryman, the Lee-Enfield could perform what was called the "mad minute," i.e., thirty rounds hitting a target 200 meters distant in one minute, a volume of fire that rivals modern semiautomatic weapons.

Although it took a little time to work out the gun's jamming problems during its combat trials in the early 1960s, the M16 has proven to be an outstanding performer with superb accuracy, handling, service length and combat effectiveness. The rifle fulfilled the U.S. military's desire to develop a lightweight modern assault rifle that could replace the semiautomatic M1 and its selective-fire counterpart, the M14. Its innovative features include lighter metal alloy and plastic construction, a simple gas reload system and the use of 5.56 mm ammunition, allowing soldiers to carry twice the amount of ammunition for the same weight of 7.62 mm rounds.

With over 75 million built worldwide, the AK-47 (a.k.a., "Kalashnikov") is a firearms legend that has probably inflicted more lethal results than any other single weapon system ever produced. Built on the same basic design as the German Sturmgewehr, it chambered an intermediate round and was built from stamped parts. The AK-47 was not only easy to produce and relatively cheap, is also proved remarkably easy to maintain and virtually immune to conditions that could easily take out other guns. Accuracy is average, but the Kalashnikov compensates for this with its ability to unleash a lethal wall of lead.

10. George Washington ClassBy the grim logic of the Cold War, submarines armed with strategic nuclear missiles did much to keep the peace. Hidden under the ocean and extremely difficult to detect, the nuclear-powered ballistic missile submarine (SSBN) was the perfect deterrent.A potential adversary knew that even if a surprise nuclear attack wiped out land-based missiles and bombers before they were launched, the SSBNs (or "boomers") would survive to retaliate.The world's first SSBN was the USS George Washington, first ordered in 1957 and commissioned in 1959. Earlier Soviet subs had carried nuclear-armed ballistic missiles, but they were diesel-powered boats with limited endurance.The George Washington's nuclear propulsion enabled it to remain underwater for months without surfacing. Each of the five boats in the George Washington Class carried 16 Polaris missiles, giving a single submarine the capability to devastate an opponent's heartland.

9. Type XXI U-boat

The Allies were fortunate that the Type XXI U-boat arrived too late to see combat. Had it been deployed before the end of war, it could have had a devastating impact on the Battle of the Atlantic.

The Type XXI had numerous advanced features for its time, including high-capacity batteries that enabled it to remain underwater for days, a streamlined hull, and a snorkel to recharge the batteries while underwater. With an underwater speed of 17 knots, it could actually outrace most surface warships.

8. Typhoon Class

Soviet-built Typhoons are the largest submarines in the world, weighing in at 48,000 tons (a U.S. Ohio-class ballistic missile sub weighs less than 20,000 tons, while an Arleigh Burke-class destroyer is only about 9,000 tons).

Despite its size, the six Typhoons that were built were surprisingly quiet and hard to detect. They carried 20 SS-N-20 (NATO code name "Sturgeon") ballistic missiles equipped with multiple nuclear warheads, as well as anti-ship guided missiles and torpedoes. The boats featured multiple pressure hulls for greater strength.

7. Sentoku Class

A submarine that's an aircraft carrier seems like mating a fish and an elephant, but that didn't stop several navies from trying.

The Imperial Japanese Navy's I-400 Sentoku Class boats of World War II were 6,500 tons, almost three times the size of U.S. Gato Class subs, and about the same displacement as a U.S. George Washington-class nuclear-powered missile sub from the early 1960s.

The three Sentoku boats each carried three torpedo-equipped M6A Seiran floatplanes that would be launched by catapult, and then ditch in the water upon their return.

6. X-Craft

While many of the most famous submarines were giants, at the other end of the sub spectrum were the midget submarines. Britain's X-craft were used for special attack missions in heavily defended harbors that were impervious to conventional submarine attack.

Their most famous raid was in 1943, when X-craft damaged the German battleship Tirpitz in a Norwegian harbor. The tiny 27-ton submarines were towed by larger boats to the target area, where they were cast off to make their way to the target. The crew would plant explosive charges before returning to the mother sub.

5. USS Nautilus

The USS Nautilus was the world's first nuclear-powered submarine.

Until the Nautilus, submarines were powered by diesel engines that could not be used underwater. Subs could either expose themselves on the surface when using their diesels, or run submerged on batteries that had limited power.

But a nuclear-powered submarine could spend its entire voyage submerged and hidden. In 1955, for her maiden voyage, the Nautilus traveled 1,100 nautical miles - the longest submerged cruise in history at that time.

4. T Class

Known also as the Triton Class, these boats formed the backbone of the British submarine force during World War II.

Displacing about 1,500 tons, T Class subs packed a heavy punch of 10 torpedo tubes. However, they all fired forward, compared to other subs that could fire torpedoes with both bow and stern tubes.

American Gato Class submarines were the bane of Japanese merchant ships during World War II. Fast, well-armed and with good range, they were well-suited for the undersea war against Japan.

Gatos displaced about 1,500 tons, and were armed with six bow and four stern torpedo tubes. They could travel 20 knots on the surface and nearly 9 knots submerged.

2. Seawolf Class

At more than $4 billion apiece, Seawolf Class submarines were the most expensive in history. But they were designed for a mission that brooked no failure; stalk and destroy Soviet ballistic missile subs before they could launch their weapons.

Designed to be extremely fast and extremely quiet, the high price tag and diminished Soviet submarine threat with the end of the cold war caused the program to be cancelled after the first three boats were delivered.

One of them, the USS Jimmy Carter, has since been converted into a spy sub.

1. Type VII U-Boat

Perhaps the ultimate symbol of the deadly underwater predator, the Type VII U-boat may be the most famous submarine class in history.

It was also the most numerous, serving as the workhorse of the German submarine forces in World War II. At around 900 tons displacement, and armed with five torpedo tubes, the Type VII was smaller than the big American fleet boats, but it came perilously close to winning the Battle of the Atlantic.

But the cost was frightful; of 1,100 U-boats constructed in World War II - including 700 Type VII's - more than 800 were lost. More than 75 percent of U-boat crewmen perished.

No 1.Barack Obama

President-United States of America-Age: 48

Presides over world’s largest, most innovative, most dynamic economy; commander-in-chief of planet’s richest, deadliest military; finger on button of nuclear arsenal containing more than 5,000 warheads; head-of-state of world’s sole superpower; his Democrats have majorities in both U.S. House and Senate; recently awarded Nobel Peace Prize, apparently for general awesomeness.

2 Hu Jintao

President-People’s Republic of China-Age: 66Paramount political leader of more people than anyone else on the planet; 1.3 billion Chinese, some 70% in their prime working years of ages 15 to 64 powering world’s low-cost workshop, transforming nation. "Coming-out party" at 2008 Beijing Olympic Games showcased young, modern, harmonious society. Credible estimates have China poised to overtake U.S. as world’s largest economy in 25 years—although, crucially, not on a per-capita basisHu Jintao.

3 Vladimir Putin

Prime Minister-Russia-Age: 57Prime Minister might as well be known as Czar, Emperor and Autocrat of All the Russians. Vastly more powerful than his handpicked head-of-state, President Dmitry Medvedev. Presides over one-ninth of Earth’s land area, vast energy and mineral resources. Former KGB officer unafraid to wield his power; invading Georgia, cutting off natural gas supplies to Ukraine or Western Europe (again). Declared nuclear power has veto on U.N.’s Security Council. The anti-Obama: "I’m deeply convinced that constant change is not for the better."Vladimir Putin

4 Ben S. Bernanke

Chairman-Federal Reserve-U.S.-Age: 55Former chairman of Princeton’s economics department and noted Great Depression scholar now guiding world’s largest economy through Great Recession; has overseen massive growth in Fed’s balance sheet, from less than $900 billion in liabilities in August 2008 to more than $2.1 trillion today. With federal funds rate now effectively 0%, the so-called Bernanke Doctrine calls for using monetary policy to stave off deflation. "The U.S. government has a technology, called a printing press, that allows it to produce as many dollars as it wishes at essentially no cost."

5 Sergey Brin and Larry Page

Founders-Google-U.S.-Age: 36If knowledge is power, maybe information is too. Brainy duo met in Stanford computer science Ph.D. program, now trying to put all the world’s information at your fingertips. Known for collecting best and brightest young tech talent at Mountain View, Calif., "Googleplex"; employees encouraged to spend one day a week on personal projects; company often named "Best Place To Work" in America. Google guys’ combined net worth of $30.6 billion would place them third on the Forbes 400. Yet despite professed intentions to "do no evil," Google is blamed in some quarters for decimating traditional publishing, journalism. Brin: "Some say Google is God, others say Google is Satan."

6 Carlos Slim Helu

Chief executive-Telmex-Mexico-Age: 69

World’s third-richest man is dominant economic force in Mexico, personal fortune equivalent to some 2% of Mexican GDP. Telecommunications monopolist: His Telemex owns 90% of Mexico’s fixed telephone lines; his TelCel has 90% of wireless market. Also head of group dedicated to improving Mexico’s roads, energy infrastructure, water supply. New focus, media: Last fall snapped up 7% stake in the New York Times Co., largest after Sulzberger owner-family. "I think it’s perverse to believe there shouldn’t be strong companies in poor countries."

7 Rupert Murdoch

Chairman-News Corp.-U.S.-Age: 78"The man who owns the news" still believes in print, not afraid to use vast media holdings to further personal political views. Media empire includes leading British (the Times), Australian (The Australian), American (The Wall Street Journal) newspapers, in addition to tabloids like the New York Post and The Sun (U.K.). Also movies (20th Century Fox), books (HarperCollins), television (Fox, BSkyB), online (MySpace). Weak ad-marketing hurting his News Corp.: net loss of $3.4 billion in fiscal 2009, stock off March lows, but still well below 2007 levels, when he made a $5.6 billion gamble on Dow Jones. Accused Google of stealing content; threatened to block search engine from indexing his Web sites. "Quality journalism isn’t cheap."

8 Michael T. Duke

President, CEO and Director-Wal-Mart Stores, Inc.-U.S.-Age: 59

Runs world’s largest retailer, more country than company: $401 billion in annual sales, 2 million employees, 8,000 stores. Wal-Mart alone is China’s eighth-largest trading partner. Largest private-sector employer in U.S.; favorite target of unions; blamed and praised for backing Obama health care proposals, shifting economic power from manufacturers to retailers, from mom-and-pop to big box. "I am competitive by nature and I want to win."

9 Abdullah bin Abdul Aziz al Saud

King Saudi Arabia-Age: 85Absolute ruler of desert kingdom that contains the world’s largest crude oil reserves, two holiest sites in Islam. State-owned oil producer Saudi Aramco most profitable company on Earth, earns more than $200 billion a year, has reserves of 260 billion barrels or 25% of planet’s known supply. Ultimate succession unclear: 85-year-old king’s official heir is 81-year-old Crown Prince Sultan bin Abdul Aziz Al Saud. In 2006, established committee of senior princes to ensure smooth transition in the event both become incapacitated.

10 William Gates III

Co-Chair-Bill & Melinda Gates Foundation-U.S.-Age: 54Richest man in the world monopolized, transformed software business. More than 85% of world’s hundreds of millions of computer users stare at, struggle with, Microsoft products on daily basis. Second act: Saving the world. Still Microsoft chairman, but now devotes day-to-day to his Bill & Melinda Gates foundation, the largest charity on Earth with $34 billion endowment. Foundation devoted to reducing hunger, improving education and fighting diseases like malaria, tuberculosis and AIDS.